The present invention relates generally to electrical lamps and, more particularly, to an assembly formed of gas discharge lamps which may be coupled in a variety of differing configurations.
Three basic types of light sources are available. They are incandescent lamps, fluorescent lamps and gas lamps wherein gas lamps include gas discharge lamps. Incandescent lamps produce light by electrically heating high resistance filaments thereby causing the filaments to glow. The filaments are usually formed as coiled tungsten wires and heated to incandescence by an electrical current passing through the filaments when the lamp is operating. The coiling of the tungsten filament increases the light producing efficiency. Filling an incandescent lamp with inert gas rather than normal atmospheric gases reduces tungsten evaporation and allows higher operation temperature of the filament.
Fluorescent lamps provide better energy efficiency than incandescent lamps because they convert more electrical energy into light energy and less into thermal energy. Therefore, fluorescent lamps are often preferred over incandescent lamps to reduce power consumption and heat generation. However, a fluorescent lamp circuit usually requires a ballast device. Ballast devices suitable for this purpose may be relatively large. Sometimes a starter device is also needed for fluorescent lamps. Since both of these devices can be somewhat bulky they can hamper the mounting of fluorescent lamps in some locations where it would be useful to save energy. This may be especially true where an incandescent light fixture is being replaced with a fluorescent fixture which must fit in the same amount of space.
Several methods of substituting fluorescent lamps for incandescent lamps to save energy have therefore been developed in the prior art. In U.S. Pat. No. 4,683,402, a fluorescent lamp adapter uses a toroidal ballast that fits around a fluorescent lamp socket. This design reduces the overall volume of the fluorescent adapter and allows threadable insertion of the adapter into a conventional incandescent lamp socket. In U.S. Pat. No. 4,645,283 a fluorescent lamp adapter has its ballast detachably connected to the side of the adapter case. This side mounted ballast may be removed to provide clearance so that the main adapter case can be threadably mounted into a lamp socket. The threaded base of the adapter case of this device ratchets to allow it to rotate after threading is complete. Once the main adapter case is properly positioned the side ballast can be attached. See also, example, U.S. Pat. Nos. 3,953,761; 4,363,083 and 4,841,193. These references contain other examples of substituting fluorescent lighting systems for incandescent lamps. While the use of these fluorescent lighting systems is an improvement over incandescent lamps, these fluorescent systems still have drawbacks.
Thus, rather than fluorescent lamps, other lamps using inert gases are sometimes used. Helium, neon, argon, krypton, radon, and xenon are elements which may serve as the inert gases for these lamps. Neon and argon are used in lighting tubes such as arc discharge tubes. Discharge lamps of the gas discharge type produce light by establishing an arc between two electrodes in an atmosphere of the gas at low pressure. Electrodes may also be used in high intensity gas discharge lamps. In the case of some high intensity gas discharge lamps the electrodes are located a few inches apart, at opposite ends of a small, sealed, translucent or transparent arc tube.
Lamps formed with inert gases can be formed into elongated shapes. There are numerous applications for elongated lamps of this type. One application is in situations where it is desired to arrange a plurality of lamps close together. For example, the elongated lamps may be arranged in a long straight line configuration, in a parallel configuration, or in angled or curved configurations. Such configurations are useful for lighting shelves, countertops, mirrors, and other common regions with similar geometries. In these applications it is desirable to avoid bulky ballast and starter devices.
U.S. Pat. No. 2,344,935, issued to Whitaker, describes an arrangement of elongated lamp fixtures. The fixtures taught by Whitaker include a channel member containing a starter and a control unit. Each fixture of the arrangement is also provided with a pair of spaced apart sockets at the ends of the channel member for receiving a replaceable fluorescent lamp. Each of the two sockets is provided with either a male connector or a female connector so that one fixture can be plugged into another to form a straight line of illumination fixtures. Angle blocks are also described in Whitaker for connecting the fixtures together at different angles. U.S. Pat. No. 2,652,483 to Laidig et al. describes arrangements of semicircular fluorescent lamps connected together in various configurations using connector blocks and other types of connection devices.
Neon tube lighting systems are also well known in the prior art of illumination devices. These lighting systems often include a plurality of neon tubes. In these systems the end of the material forming each neon tube may be bent back and the bent back portion of the tube may contain an electrode for causing the neon gas to glow. The electrode contained in this way may be connected by a wire to an electrically conductive metal cap. The metal cap may have a wire protruding from its end face for electrical connection to either an energy source or to the metal cap of an adjacent tube when two tubes are aligned in an endwise fashion and joined to each other.
It is also known in the art to provide electrical connectors for neon tubes supported in an end-to-end fashion. Examples of such connectors are shown in U.S. Pat. Nos. 1,817,543, 2,175,155, 2,238,589 and 4,947,301. U.S. Pat. No. 2,238,589 to Hensler, for example, discloses one such electrical connector having a pair of tubular sections. Each tubular section of the Hensler illumination system includes a closed outer end and telescopically engaged inner ends. The inner ends are axially interfitted within each other. A spring like electrical connector element is used to connect the ends of adjacent tubes.
A similar system is shown in U.S. Pat. No. 2,175,155 to Miller. The Miller reference discloses a jumper connector having a pair of hook ends. The hook ends are disposed in a confronting relation with each other. Each hook end has a tubular stem and the stems are adapted to interfit with to each other to form a telescoping structure. A coiled wire provides the electrical required connection for energizing the lamp in the Miller system.
It is well known to attach lamps serially wherein all of the serially attached lamps are in a single series electrical connection with each other. This series electrical arrangement has the disadvantage that if one bulb in the series fails to light, the entire series goes out. Furthermore, it may be difficult to determine which light in the series connection has failed. Also, in series electrical connections such as these, the voltage available for each light is the source voltage divided over the total number of lamps in the series. If, on the other hand, all the lamps are in a parallel arrangement, failure of one of the lamps does not affect the others. However, in a parallel arrangement such as this each lamp in the circuit is subjected to the full value of the line voltage unless a transformer is used.
Additionally, lamps may be joined in configurations which include both series electrical connections and parallel electrical connections. A common application of this type of configuration is in the field of miniature push-in type lamps. Normally, in a series-parallel configuration of lamps, the lampholders in each series set are interconnected using multiple short lengths of insulated lead wire connected to contact plates. This arrangement is shown, for example, in U.S. Pat. No. 3,104,924. The lead wires to and from the first and last lampholders in each series set are connected, respectively, to parallel wires from a power source such as a wall plug.
Alternatively, the connection to the parallel wires is made by interrupting the parallel wires at the first and last lamps of each series set and connecting both interrupted ends to the appropriate contact plate of the first and last lampholders. Hence, assembly of a series-parallel string of miniature lights has included the handling and end-stripping of a number of pieces of wire. Altering configurations of this type is thus time consuming. Additionally, there has been a need to wind the series wires and the parallel wires together between the lamps for ease of handling when deploying a string of lamps.
The above-described prior art connections do not provide electrical and mechanical connections between endwise-supported neon tubes which are secure enough and versatile enough for safe, convenient use. These prior art devices are also difficult to use without damaging the fragile neon tubes in many cases. Thus it is desirable to find a way to couple these prior art lamps which allows the lamps to be disposed in differing configurations with respect to each other while remaining security coupled in electrical contact and mechanical contact.
Briefly, the present invention is directed to an elongated neon lamp which is adapted to permit an assembly multiple neon lamps to be electrically coupled to each other and energized with a single low voltage DC energy source. Each neon lamp in the assembly is provided with a gas discharge lighting tube and at least two external connectors which are wired in parallel with each other within the neon lamp. Power from the single energy source is applied to either of the external connectors in order to power the neon lamp. A high voltage, high frequency inverter power supply is provided within the neon lamp for receiving the low voltage DC energy and producing a voltage suitable for energizing the gas discharge lighting tube. A linking power cable with a mating cable connector at each end is coupled to one of the remaining external connectors on the neon lamp. The connector at the remaining end of the cable may thus apply the low voltage DC energy to an additional neon lamp, including the inverter power supply of the additional neon lamp, to form a lighting assembly. The connector at the remaining end of the linking power cable may be coupled to any one of the external connectors of the additional neon lamp. Further neon lamps may be attached to the lighting assembly in the same manner. In this manner energy may be distributed to a number of gas discharge tubes using a single low voltage DC energy source provided it can produce sufficient current. The external connectors may be disposed, for example, at opposite ends of the neon lamp or at spaced apart locations on one end of the neon lamp.